Method and apparatus for making sheet metal



Dec. 24, 1940. P. w. MATTHEWS METHOD AND APPARATUS FOR MAKING SHEETMETAL Filed May 9, 1935 5 Sheets-Sheet 1 ATTOR EY Dec. 24, 1940. p wMATTHEWS 2,226,500

METHOD AND APPARATUS FOR MAKING SHEET METAL Filed May 9, 1935 5Sheets-Sheet 2 INVENTOR ATTORNEY Dec. 24, 1940. P. w. MATTHEWS 2,226,500

METHOD AND APPARATUS FOR MAKING SHEET METAL Filed May 9, 1935 5Sheets-Sheet 3 INVENTOR BYf ' ATTORNE Dec. 24, 1940. P, w. MATTHEWSMETHOD AND APPARATUS FOR MAKING SHEET METAL Filed May 9, 1935 5Sheets-Sheet 4 Y E N R O T T A Dec. 24, 1940. P. w. MATTHEWS METHOD ANDAPPARATUS FOR MAKING SHEET METAL Filed May 9, 1935 5 Sheets-Sheet 5ATTORNEY U 0 N H 2.

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Patented Dec. 24, 1940 UNITED STATES PATENT OFFICE METHOD AND APPARATUSFOR MAKING SHEET METAL Percy W. Matthews, Pittsburgh, Pa., assignor ofthirty-eight one-hundredths to Edgar J. Grifiiths, Pittsburgh, Pa...nineteen one-hundredths to Joseph F. Brandenburg, Larchmont, N. Y., andfive one-hundredths to Charles W. Neill, West Englewood, N. J.

Application May 9, 1935, Serial No. 20,587

21 Claims. 80--35) This invention relates to method and apparatus and toprovide an improved construction for zonefor making sheet steel in hotand cold strip rolldivided rollers which are employed to maintain ingmills. a uniform temperature across the width of the The invention isapplicableto continuous strip strip. mills in which the metal passes inone direction -Other objects, features and advantages of the throughsuccessive roll stands, and to cold rolling invention will appear or bepointed out as the mills which pass the strip back and forth throughdescription proceeds.

a single roll stand or tandem roll stands between In the accompanyingdrawings, forming part reels on which the strip is wound and unwound.hereof:

The term strip is used in this specification in a Fig. 1 is adiagrammatic side elevation of the broad sense to describe the sheetmetal operated last three stands of a continuous strip mill, and upon bythe rolling mills, but the term is not ina flying shear beyond the lastroll stand, with tended to be a limitation on the width of the sheetapparatus between the successive stands and bemetal because somefeatures of the invention are tween the last mill stand and the flyingshear for especially adapted for the production of sheet controlling thetemperature and tension of the metal of great width. sheet metal inaccordance with this invention.

One object of the invention is to provide im- Fig. 2 is a top plan viewof the roll stands and proved method and apparatus for producing flatthe temperature and tension controlling apparasheet metal which is freefrom warps and buckles tus of Fig. 1. after it cools. Inability toobtain a fiat product Fig. 3 is a diagrammatic side elevation of a inwide strips has put definite limitations on the single-stand coldrolling mill, with coiling appawidth of the sheet metal rolled inaccordance ratus at both ends of the strip which passes with the priorart. According to one feature of through the mill, and temperature andtension this invention the temperature of the strip is concontrol meansbetween the roll stand and each trolled at and between roll stands, orbetween coiling apparatus. other apparatus which acts on the strip, soas Fig. 4 is a view similar to Fig. 3 with the addito maintain asubstantially uniform temperature tion of a tandem roll stand and meansbetween across the entire width of the strip and prevent the two rollstands for controlling the temperauneven rolling and the formation oflocked up ture and tension of the strip. stresses which make the stripwarp or buckle. Fig. 5 is an enlarged side view, partly in section,

Another object of the invention is to maintain showing a portion of thetension and temperature a constant tension on the strip between the rollcontrol means which is located between two of the stands of a hotrolling mill. Another object is to roll stands of Fig. 1. tension astrip during a hot or cold rolling opera- Fig. 6 is an enlarged viewshowing the motor of tion and keep the tension uniform regardless ofFig. 5 with means for automatically varying the variations in the amountof slack between roll torque of the motor in response to changes in thestands or changes in the angle of deflection of the slack and deflectionof the strip in order to mainstrip. tain a substantially uniform tensionin the strip.

The invention includes novel apparatus for Fig. 7 is a top plan view ofa portion of the maintaining a constant uniform tension on the apparatusshown in Fig. 5 with the motor control run of strip between two rollstands by means of means of Fig. 6 also shown but on a reduced scale. avariable-torque motor equipped with means for Figs. 8 and 9 are enlargedsectional views on the varying the torque in accordance with changeslines 8-8 and 9 -9 of Figs. 6 and 5, respectively. in the deflection ofthe strip. In another form Fig. 10 is a, side elevation of an embodimentof of the invention a constant-torque device is comthe invention formaintaining a substantially unibined with apparatus for changing themechanform tension in the strip by means of a constantical advantagewith which the device tensions the torque motor instead of thevariable-torque mechstrip as the angle of deflection of the strip variesanism shown in Figs. 6 and 7. with the slack between the roll stands.Fig. 11 is a sectional view on the line I l-l l of Another object of theinvention is to provide Fig. 10. an improved method and apparatus forremoving Fig. 12 is a view, partly in section and partly scale from thestrip during the rolling'operation. schematic, showing the full-widthfinding device Other objects are to provide improved control and theelectric control circuits for the apparatus. mechanism responsive to thepassage of the full Fig. 13 is an enlarged plan view taken on the widthof material at the forward end of the strip, line |3l3 of Fig. 12.

Fig. 14 is a sectional view on the line l4=l4 of Fig. 13.

Fig. 15 is a view, on a reduced scale, showing typical irregular frontand rear ends of the metal strip.

Fig. 16 is a sectional view on the line Iii-l6 of Fig. 12.

Fig. 17 is a top plan view of the limit switches shown in Fig. 12.

Fig. 18 is an enlarged fragmentary detail view, mostly in section,showing the construction of one of the zone-divided rollers.

Figs. 19 and 20 are sectional views on the lines I 9-H and 20-20,respectively, of Fig. 18.

Fig. 1 shows the three last roll stands H, l2 and I 3 of a continuoushot strip mill. The 4- high roll stands shown are representative of rollstands in general, since other types can be used with this invention. Alooper unit Il is located between each of the roll stands H, l2 and I3and has rollers l5 and IS in contact with the metal strip between 'theseroll stands. Similar looper units may be located between all of thestands of a continuous strip mill, but if looper units are not betweenall of the roll stands, they should be between the last stands wherethey are most effective.

A fullwidth finding device I1 is associated with each of the looperunits i l to control the operation of the looper units I4 to control theoperation of the looper unit so that no tension is applied to the stripuntil the full width of the metal at the front end of the strip hasentered the next roll stand beyond the looper unit.

The metal strip I8 travels from right to left in Fig. 1 and the frontend of the strip is guided into the looper units and roll stands by achute I 9. This chute is made up of a number of sections located betweenthe roll stands and looper units, and any other places where the forwardend of the strip needs support at the beginning of a rolling operation.

After leaving the last rolling pass l3, the strip 18 is guided by thechute I9 to a looper unit 20 and then into the pinch-rolls 2| of aflying shear 22. The looper unit 20 differs from the units M in that ithas only one roller. All of the looper units may be similar to thelooper units Id of the unit 20. The construction will be described fullyin the explanation of Figs. 5 and 7.

Referring again to Fig. 1, the strip l8 passes from the pinch-rolls 2|into feed rolls 26, which move the strip between the knife drums 25 ofthe flying shear. Rollers 26 of the flying shear delivery table areshown to the left of the knife drum.

Pipes 28 deliver sprays of steam, water or other fluid against the upperand lower sides of the strip l8 to remove scale. There is a break in thechute I9 to permit fluid sprayed from the lower pipe 28 to reach thestrip l8, and there is another break to prevent the chute from coveringa luminous tube 29 of the full-width finding device l1.

Fig. 2 shows motors 3| with reduction gearing 32 connected with millpinions 33 which drive the rolls of the roll stands I l-'|3. .Fig. 2shows the relation of the looper units and roll stands. The chute l9,full-width finding devices ill and the spray pipes 28 are omitted fromFig. 2.

The rollers I 5 and 16 of the looper units are preferably zone-dividedrollers for controlling the temperature of the hot strip IS in a mannerwhich tends to equalize the temperature across the entire width of thestrip. The construction and' operation of. these zone-divided rollerswill be described in detail in the explanation of Fig. 18. For thepresent it is sufiicient to understand that these rollers are dividedinto several cooling zones, each of which extends axially for a portionof the length of the roller and each of which is substantiallyindependent of the others in its cooling effect. Hot sections of thestrip near the center can be cooled more. than sections which are nearerthe edges and at a lower temperature so that the temperature of thestrip becomes substantially constant across its entire width. The rollsof the roll stands H-I3 are also preferably zone divided.

Unless the temperature is substantially uniform across the entire widthof the strip, the gauge of the metal is not absolutely uniform and thereare locked-up stresses which make the strip warp or form into waves andbuckles. The looper units I 4 and 20 tension the hot strip to anydesired limit. When the looper rollers and those of the roll stands arezone divided, and the strip is rolled to a uniform gauge, substantiallyfree from warps and buckles, the tension imparted to the strip may belight and intended primarily to take up slack between the roll stands.When some or all of the rollers in contact with the strip are not zonedivided, and the cooling is not sufficiently uniform, or for some otherreason the strip is objectionably wavy or warped, the tension impartedby the looper units can be increased to stretch the metal andsubstantially remove the waves and warp. Even when the temperaturecontrol effected by the zone-divided rollers is sufficient to obtain asubstantially flat strip, the looper units can be used to put the stripunder any tension wanted for the rolling operation; or to stretch themetal between roll stands if such a working of the metal between theroll stands is desired. The looper units maintain a uniform tension inthe strip regardless of changes in the deflection.

An embodiment of the invention in a singlestand cold rolling mill isshown in Fig. 3. Coiling apparatus, comprising reels 35 and 36, islocated on both sides of a roll stand 31, and passes the cold strip 38back and forth through the roll stand 31 until the metal is rolled tothe desired gauge. A looper unit 20 is located between the roll stands31 and each of the reels 35 and 36. During the cold rolling of the strip38 it is subject to a constant and uniform tension as it passes from theuncoiling reel to the coiling reel. Rollers 39, which are preferablyzone divided, are located on fixed axes in positions to prevent thediameter of the coils on the reels from affecting the angle ofdeflection across the looper roller. In addition to taking up slack, thelooper units can be employed to give the strip any amount of tensiondesired and to provide any desired envelopment of the strip materialaround the rollers with which the strip is in contact. great enough toput the strip under a predetermined tension for rolling, or to stretchout any waves or other unevenness of the strip, or to stretch the entirestrip to work the metal.

Considerable heat is generated in the metal when it passes through theroll stand 31 and un even cooling of the strip is likely to give itdifferent temperatures across its width so that in its next pass throughthe roll stand it will be rolled with stresses tending to warp andbuckle the strip. The rollers l6 are preferably zone divided, for thepurpose of equalizing the temperature across the width of the stripsimilarly to This tension may be made the rolls of Fig. 1. The rolls ofthe roll stand 31 are preferably of zone-divided construction also.

The apparatus shown in Fig. 4 is a cold strip mill similar to that ofFig. 3, with the addition of another roll stand 46 in tandem with theroll stand 31, and a chute I9, looper unit I4, and full-width findingdevice II between the roll stands as in Fig. 1.

Figs. 5 and 7 show the construction of one of the looper units. When thefront end of the strip l8 comes from the working rolls of the roll stand12, it is supported by the chute I9 and passes under the roller I5, overthe top of the roller l6, under the other roller I5, through thefull-width finding device I1, and then between the upper and lower spraypipes 28, and into the working rolls of the next roll stand I3.

An inclined .portion 42 of the chute I9 is con nected to the horizontalportion of the chute by a hinge 44 and has its free end supported by arod 45. This inclined portion of the chute raises the front end of thestrip so that it contacts with the upper part of the roller I6 andpasses over this roller, as shown in Fig. 5. The roller I6 and theinclined portion of the chute comprise means for giving the strip aninitial deflection so that during the operationof the rolling mill therun of strip between the roll stands I2 and I3 will not approach astraight line where the control of tension becomes very critical.

The ends of the roller I 6 are journaled in blocks 4! which slidevertically in guides 48 of a frame 49. Both of the blocks 41 areconnected to a horizontal support 5I, and this support is raised andlowered by a rack bar 52. The upper end of the rack bar is connected to,or integral with, the support 5 I, and the lower end of the rack barbears against a roller 53 with flanges 54 (Fig. 9) for preventingdisplacement of the rack bar 52 out of its vertical position. A pinion56 meshes with teeth on the rack bar 52. Flanges 58 extending along bothsides of the teeth of the rack bar 52 contact with the hub of the pinion56 and hold the rack bar against the roller 53.

The roller 53 turns on a shaft journaled in downwardly extending lugs ofthe frame 49. The pinion 56 is secured to a drive shaft 66, which isalso journaled in lugs of the frame 49. There are limit switches 6I onthe drive shaft. The purpose of these switches will be explained in thedescription of the control mechanism. The drive shaft 66 connects with atorque motor 62, shown in Figs. 5 and '7.

When there is no power supplied to the motor 62, the rr .ler I6 occupiesthe position shown in Fig. 5, with the blocks 41 resting on springs 63.During operation of the rolling mill it is possible for the roller I6 tobe moved lower than the initial position shown in Fig. 5 by compressingthe springs 63, but in normal operation of the rolling mill the slack inthe strip is always greater than that produced by the initial deflectionimparted to the strip and the roller I6 never moves as low as theposition shown in Fig. 5. The inclined portion of the chute is hinged sothat it can move down to permit the strip to move lower than its posiionof initial deflection and avoid breaking in case of some abnormaloperation which causes almost all of the slack to be taken up before anattendant or automatic control means can correct the trouble.

' The rollers I5 turn on axles connected to the upper ends of links 64.The lower ends of the links 64 have pivot connections with the frame 49.Links 65 connect the axles of the rollers I5 with the blocks 41. Theselink connections provide strong and simple supporting means for therollers I5, but the link movement is not an essential feature of theinvention and the links 64 can be made integral parts of the frame 49and sufficiently strong so that the links 65 are not necessary. In Fig.5 the rod 45 is connected to the links 65 to rise and fall with theblocks 41.

When the looper unit is in operation and the roller I6 rises into anelevated position as indicated in dotted lines in Fig. 5, the strip I8flexes at the rollers I5. There are two important advantages in havingthese looper rollers in the relation illustrated. The strip is givenreverse bends, which are very effective in loosening scale forsubsequent removal by the spray pipes 28, and the amount of slack whichcan be taken up with a given displacement of the roller I6 is greaterwith the three-roller combination than if the roller I6 alone deflectedthe strip in an angle extending all the way to each of the roll standsI2 and I3.

The break in the chute I9 at the spray pipes 28 has sloping edges sothat the front edge ofv the strip cannot catch in this break. Adifferent provision for preventing the front edge of the strip fromcatching in the break at the luminous tube 29 will be described in theexplanation of Figs. 12-14. Such a provision may also be used at theslots for the spray pipes. The chute I9 has a sloping cover just aheadof the roll stand I3 for guiding the front edge of the strip into thebite of the rolls.

As the deflection of the strip increases, a constant upward force on theroller I6 produces progressively less tension in the strip. In order tomaintain a constant uniform strip tension, therefore, it is necessary toincrease in a definite relation the force with which the roller I6 isurged upward as the deflection of the strip increases. This can beaccomplished by increasing the torque of the motor 62. The mechanismwhich varies the motor torque is shown in detail in Figs. 6 and 8.

The supply of electricity to the motor 62 is controlled by a rheostat61, which has two rows of taps 68, with the taps of the respective rowsstaggered so that a contactor 69 of an arm I8 is always in contact withat least one of the taps 68. The contactor bears against a strip I2 tocomplete the circuit through the rheostat 61. With the arm I in theposition shown in Fig. 6, the power of the motor is at a minimum, orthat necessary to give the strip the desired tension when the deflectionis at its smallest value.

There is a cam I4 on the shaft of the motor 62, and a cam-follower atthe lower end of a lever I5. The lever I has a pivot connection I6 withthe motor frame or some other convenient stationary structure. Thefollower at the lower end of the lever is held against the cam I4 by aspring 11 connected at its opposite ends to the lever and the motorframe. A link I9 connects the lever I5 with the arm In. As the shaft ofthe motor 62 turns, the cam I4 shifts the lever 15 and moves the arm I0to vary the torque of the motor 62. The angular movement of the cam I4is proport onal to the displacement of the roller I6. The contour of thecam I4 is designed to move the arm I9 and change the motor torque insuch a manner that the tension imparted to the strip I8 remains constantregardless of changes in the deflection of the strip.

The correct outline for the cam I4 is most easily determined bycomputing the upward force on the roller I6 necessary to produce thedesired uniform tension in the strip with certain chosen deflections.The closer together these deflections are taken, the more accurate thecam outline will be. These necessary forces are first obtained withreference to roller displacement, but this is easily converted toangular displacement of the motor shaft. Adding to this knowledge themotor torque corresponding to each tap 88 of the rheostat, the necessaryradius of the cam for all of the chosen displacements can then beaccurately determined.

Figs. 10 and 11 show another form of looper unit which is similar inconstruction to the unit illustrated in Fig. 5 except that it hasdifferent kind of mechanism for raising the roller IE to tension thestrip. Cables 8| are attached to the upper ends of the blocks 41. Thesecables wrap around drums 82 on a shaft 83 journaled in brackets 84 whichextend upward from the frame 49. A large drum 86 is secured to the shaft83 near one end and a cable 81 wraps around the drum 86 at one end andaround a grooved drum 88 at the other. The grooved drum 88 is fastenedto the shaft of a constant-torque motor 90. The radius of the grooveddrum 88 varies to change the mechanical advantage of themotion-transmitting connections between the motor 90 and the blocks 41in accordance with changes in the deflection of the strip and variationsin the angularity of the connecting cables so that the constant uniformtorque of the motor 90 is transmitted to the roller I6 as a force whichso varies with the position of the roller I6 that a uniform, constanttension is maintained in the strip.

The angular movement of the drum 86 is limited because it is on the sameshaft with the limit switches 8|, but the large diameter of the drum 86with respect to the grooved drum 88 makes it possible to have the motor90 make a number of complete revolutions in moving the roller I8 fromits position of minimum strip deflection to its maximum deflectionposition.

Fig. 12 shows the full-width finding device and the control circuitsthrough which this device controls the operation of the looper unitmotor and the supply of fluid to the spray pipes 28.

A swinging finder 92 comprises a photoelectric relay 93 enclosed in anopaque housing and responsive to light which enters through a longsleeve 94. This sleeve is the only light-entrance into the photoelectricrelay housing so that only light in line with the sleeve can control thephotoelectric relay. The finder 92 is supported from a frame 95 forangular movement transversely of the strip I8. The finder swings throughan angle which causes the sleeve 94 to travel from a position in linewith the edge of the strip to a position in line with the center of thestrip. A similar finder 91 containing a photoelectric relay 98 swingsacross the other half of the strip I8. Unless the strip completelycovers the luminous tube 29, light from this tube will reach the findersat some point during their swinging movement. For a narrow strip, onefinder swinging across the full width of the strip would be sufficient,but more than one finder reduces the time required to detect the fullwidth of the strip and reduces the amount of full-width material whichmay pass through the device before it operates the control apparatus.Gear motors IOI and I02 on the frame 95 are connected with the swingingfinders 92 and 91 by links I03 and I04.

In addition to the luminous tube 29, the swinging finder 92 receiveslight also from a lamp I06 carried by a block I01 at the edge of thestrip I8. The block I! is supported from a rod I09 which extends throughthe frame 95 and has a threaded end passing through a hand-wheel I I0.The block IN is urged against a head H2 on the rod.l09

by a spring H3, and the rod is shifted trans-' versely of the strip byturning the hand-wheels I I0.

The lamp I06 receives electricity through a conductor I I 0 from acontact I I on the top of the block I0'I. A contact II! on a rod H8 isheld against the contact II5 by a spring H9, which is compressed betweenthe frame 95 and a collar on the rod II8. There is a dash-pot I2I at theend of the rod II8.

The contact H1 is connected with a lighting circuit I22 through anormally closed push-button switch I23, which can be operated at anytime to extinguish the lamp I06.

A lamp I24 at the edge of the strip under the swinging finder 91 issupported by structure similar to that described for the lamp I06 andreceives its electricity through similar contacts. A description of theoperation of the structure on one side of the strip is, therefore,sufiicient.

As long as the swinging finder 92 receives light from the lamp I06, thephotoelectric relay 93 is open and the swinging finder 92 remainsstationary. The block I 01 has a sloping face I25 (Fig. 16) and itsposition is adjusted by means of the hand-wheel IIO (Fig. 12) so that asthe strip enters the full-width finding device, the edge of the stripstrikes the sloping face of the block and pushes the block outwardagainst the pressure of the spring II3. This movement of the block I0Imoves the contact II5 away from the contact I I I and breaks the circuitto the lamp I08. When the swinging finder no longer receives light fromthe lamp I06, the photoelectric relay 93 closes and supplies power toclose a normally open contactor I 21. The closing of this contactorcompletes a circuit from a power line I28 through a speed control panelI29 to the gear motor IOI. When this motor starts it swings the finder92 counterclockwise in Fig. 12.

The lamp I06 must remain extinguished until the swinging finder movesout of the range of this lamp or into the shadow of the strip I8. Thistime delay is obtained with the dash-pot I2I, which makes the movementof the contact II 1 under influence of the spring II9 slow enough toallow the swinging finder to move beyond the influence of the lamp I08before the contacts I I5 and II'I'again touch and relight the lamp.

A normally open push-button switch I3I is connected in parallel with thephotoelectric relay 93 and can be operated to close a circuit from acontrol power line I32 to the contactor I21 for manual operation of themechanism regardless of the light supplied to the photoelectric relay.

The control circuits of the photoelectric relay 98 and motor I02 aresimilar to those already described for the swinging finder 92. If eitherof the swinging finders 92 and 91 picks up light from the luminous tube29, the photoelectric relay in that finder opens and causes the swingingmovement of that finder to stop until the strip covers the tube 29. Fig.shows a typical front end of the strip I8 and it is evident that thelength of the luminous tube between the block I01 and the correspondingblock on the other side will not be shielded from the swinging findersuntil the ragged edge has passed beyond' the tube 29 and the portion ofthe strip in which the metal extends across the full width is under theswinging finders.

Contacts I34 and I35 near the center of the frame 95 are connected withthe control power line I32. Other contacts I36 and I31 are connectedwith normally open, adjustable time-delay opening relays I38 and I39. Acontact I46 carried by the swinging finder 92 bridges the contacts I34and I36 when the swinging finder reaches the limit of its inwardmovement. The closing of the ciricuit between these contacts I34 and I36supplies power to the relay I38 and causes it to close. A contact I4Icarried by the swinging finder 91 bridges the contacts I35 and I31 toclose the relay I39.

The contacts closed by the relays I38 and I39 are connected in series,and when both of these relays are closed at the same time they completea circuit from the control power line I32, through a conductor I43 toone contact I44 of the limit switch 6I. A commutator bar I46 on the drumof the limit switch completes the circuit from the contact I44 toanother contact I41 which connects with an adjustable, normally open,time-delay closing, differential contactor ME). A normally open,push-button switch I56 isconnected in parallel with the relays I38 andI39 for closing the circuit to the contactor I69 regardless of theposition of the relays.

When power is supplied to the difierential contactor I49 from thecontact I44 of limit switch 6i,

this contactor I49 closes the circuit from a power line I5I, through atorque control panel I53, to the motor 62. This torque control panel I53includes the rheostat 61 when the control circuit is designed for theembodiment of the invention shown in Figs. 5-8.

Referring again to Fig. 12, the closing of the contactor I49 suppliespower through a normally closed, push-button switch I54 and conductorI55 to open a solenoid-operated valve I56 which controls the supply offluid to the spray pipes 28. The push-button switch I54 can be opened atany time to cut oil the current which holds the valve I56 open, so thatthe valve will close and the sprays stop. A normally open, push-buttonswitch I51 can be closed to supply power to the valve I 56 at any time.

When power is supplied to the motor 62 it is also supplied to a brakeI58 on the motor to release this brake. The brake is connected in thecircuit ahead of the torque control panel I53 because it is neverdesirable to reduce the power supplied to hold the brake released whilethe motor is running.

The limit switch 6I has a commutator bar I66 which moves into positionto bridge contacts IGI and I62 when the motor 62 turns beyond apredetermined limit. When'the circuit between the contacts I6I and I62is closed, current flows from the control power line I32 to an openingsolenoid I64 of the differential contactor I49. This solenoid I64 can besupplied with current to open the differential contactor I49 at any timeby closing a normally open, push-button switch I66 which is connected inparallel with the contacts I6I and I62 of the limit switch. Anothernormally open, push-button switch I66 is connected in parallel with thecontacts I44 and I41 01 the limit switch and can be operated at any timeto close the differential contactor I49.

when the rearward end of a strip passes through one roll stand, theroller of the looper unit between thatvroll stand and the next is freeto rise without restraint from the strip tension, and the motor 62rotates until the limit switch 6I closes the circuit to the solenoid I64and opens the differential contactor I49 and the circuit to the motor62.

The limit switch 6I includes two drums, as shown in Fig. 17. The innerdrum I12 is secured to the motor shaft, and carries the commutator barI66. The outer drum I13 is secured to the inner drum by screws I15 (Fig.12) extending through arcuate slots to permit angular adjustment of thedrums with respect to one another. The commutator bar I46 is carried bythe outer drum I13.

Figs. 13 and 14 show ribs I11 over the tube 29 to prevent the front endof the strip from catching in the break in the chute I9. These ribs aresufliciently thin and are set on a diagonal so that their shadows do notafiect the operation of the swinging finders.

stands are preferably zone-divided by a similar construction. The rollercomprises an outer shell I18 into which end fittings I19 are secured.The

end fittings run in ball bearings I86 in the roller supporting frame orblocks 41. A nut I82 threads over the outer end of the end fitting I19and holds the ball bearing I86 in assembled relation with the endfitting. Seals I83 protect the ball bearing from water and dirt andretain lubricant in the bearing.

The fluid inlet conduit is made up of a series of short tubes I85extending in a line through the center of the roller. The ends of eachtube I85 are spaced a short distance from those of the next adjoiningtubes, and there is a conduit section I86 connecting each tube with thenext tube. The conduit sections I86 have two walls with a conduit I88between them. The inner and outer walls of the conduit sections I86 arejoined at spaced points by pillars I89.

The ends of both the inner and outer walls of each conduit section fitover the adjacent ends of the corresponding walls of the next conduitsection to form sliding joints I9I and I92 between the ends of the.conduit sections to allow for expansion with change of temperature. Theends of the conduit sections remote from their threaded connections withthe tubes I85 are free to slide on the tubes as the conduit sectionschange in length with temperature variation. The inner face of eachconduit section is spaced, for the greater part of its length, from thetube I85, which it surrounds, to form a heat insulating chamber I94.

A sleeve I96 surrounds each of the conduit sections I86 and throughoutmost of its length is spaced from the outside wall of the conduitsection to form a heat insulating chamber I91.

A chamber I98, between the sleeve I96 and the outer shell I18,communicates through openings 266 with the fluid inlet conduit formed bythe tubes I85. These openings 266 extend through roller is cold.Plungers 201 extend through openings in one end of the ring 205 into anannular mercury chamber 208 enclosed in the ring. The outer ends ofthese plungers 20'! contact with an abutment comprising a nut 209threaded over the end of the sleeve I96 and held in set position by alock nut 2I0. respect to the openings 204 can be adjusted by changingthe positions of the nuts 209 and 2I0 on the sleeve I96.

The ring 205 is urged toward the nuts 209 and 2I0 by a spring 2I2 whichis compressed between the ring and a collar on the sleeve I96. When thetemperature of the liquid in the chamber I90 rises, heat is transmittedthrough the ring 205 to the mercury in the chamber 208 and the expansionof this mercury displaces the plungers 201 and causes the ring 205 tomove away from the nut 209, against the force of the spring 2I2, topartially uncover the openings 20 5. A further rise in the temperatureof the liquid in chamber I98 causes the ring 205 to uncover more of theopenings 2% and increases the rate of flow of cooling liquid through thechamber I98 to counteract the temperature rise.

The zones of the roller are divided by packing 2I5 which is held inplace by nuts 2I6 threaded as may be necessary to maintain asubstantially uniform temperature across the width of the strip. Byreducing the length of the zones, the number of zones is increased, andthe accuracy of the temperature control improved. Although thezone-divided rollers of this invention are employed to cool the strip,it will be understood that the roller construction illustrated can beemployed when rolling material which must be heated by the roller. Forsuch operation the; openings 2| t are located at the other end of therings 205 so that the ring uncovers these openings as the temperaturefalls and hot fluid is supplied through the inlet conduit.

The preferred embodiments at this invention have been described, butchanges and modifications can be made, and some features can be usedwithout others, without departing from the invention as defined in theclaims.

- I claim:

1. The method of making sheet metal which comprises simultaneously andprogressively roll-' ing different portions of a metal strip to reducethe thickness while the metal is at a high temperature, and deflectingthe hot strip out of its normal run between successive points at whichthe metal is rolled by applying to the hot strip between said points aforce of sufficient magnitude to impart a consequential tension to thehot metal as it passes from one point of rolling to the next.

2. The method of rolling metal in a continuous strip mill, which methodcomprises passing a strip which is at least red hot through successiveroll stands, applying force to the hot strip between roll stands toproduce a deflection of the strip and maintain a tension in the metal,maintaining said force at a magnitude sufi'icient to stretch the hotmetal, and changing the magnitude of said force in accordance withvariations in the angle of deflection and at a rate which The positionof the ring 205 with causes the tension of the hot strip to remainsubstantially uniform when variation in the slack between roll standscauses changes in the angle of deflection.

3. The method of making sheet metal in a hot rolling strip mill in whichthe metal strip passes successively through roll stands which operatesimultaneously on different portions of the strip, which methodcomprises applying a force and deflecting the hot strip betweensuccessive roll stands, maintaining the deflecting force against thestrip to cause a tension in the metal between the roll stands during therolling of the metal, and controlling the temperature of the tensionedmetal to obtain a substantially uniform temperature across its width asit enters the next roll stand.

4. The method of making sheet metal in a hot rolling mill havingsuccessive roll stands through which the metal strip passes, whichmethod comprises passing the forward end of the strip through thesuccessive roll stands with the metal at a high temperature, imparting asubstantial initial deflection to the strip after it has passed throughone roll stand and before the forward end of the strip has entered thenext roll stand, and taking up the slack between the successive standsby imparting a further deflection to the strip in the same direction asthe initial deflection after the forward end of the strip has passedthrough said second roll stand.

5. The method of rolling thin flat metal sheets in a rolling mill havingsuccessive roll stands through which a metal strip is passed to reducethe thickness to the gauge desired, which method comprises deflectingthe metal strip between successive roll stands to produce sufficienttension in the metal to stretch said metal and remove warps and bucklesin the strip, increasing and decreasing the tensioning force inaccordance with changes in the slack between the roll stands at a ratewhich causes the tension in thestrip to re-- main substantially uniformregardless of changes which the slack variation causes in the angle ofdeflection, and equalizing the temperature of the strip by selectivecooling at various zones across its width to prevent the formation ofstresses tending to warp or buckle the strip.

6. In apparatus for rolling a metal strip to reduce its thickness, aroll stand through which the metal strip passes at one point in itstravel, other means operating upon the strip at a point spaced from theroll stand lengthwise of the strip, and a temperature-controlling rollerin contact with the run of the strip between the spaced points, saidroller being divided internally into a plurality of axially extendingzones and having means 'for producing different temperature-controlefiect from the respective zones to equalize the temperature of thestrip across its width.

'7. Apparatus for rolling sheet metal including in combination acontinuous hot strip; rolling mill with a plurality of roll stands,roller means between successive rollstands for deflecting the run ofstrip passing between said successive roll stands, said roller meansincluding one or more hollow rollers divided into several axiallyextending zones, means for controlling the temperature of the respectivezones independently to equalize passes, of a device which bears againstthe strip between the roll stands and deflects the strip at acute anglesto a straight run between the roll stands, power mechanism for movingsaid deflecting device to hold it against the strip during changes inthe amount of slack between the roll stands, and automatic meansincluded in said power mechanism for changing the mechanical advantageof said mechanism in accordance with the sine of the angle of deflectionof the strip, as the angle of the deflection changes, so that theresulting tension forces in the strip remain subthe strip in accordancewith changes in the slack and at a rate which obtains a substantiallyuniform tension in the metal of the strip during said changes in theslack.

10. The combination with the successive roll stands of a rolling mill,of means imparting an initial deflection to the metal strip while theforward end of the strip is passing from one roll stand to the next rollstand, and other means for deflecting the strip further in the samedirection and taking up the slack in the strip after the forward end haspassed through said next roll stand.

11. In a cold rolling strip mill, the combination of a roll standthrough which'a. metal strip is passed to reduce the thickness of saidstrip, reels beyond both ends of the roll stand for winding andunwinding the strip as it is passed back and forth through the rollstand, means tensioning the run of strip between the roll stand and atleast one of the reels, said means comprising a roller which contactswith and deflects the strip, said roller being divided internally into aplurality of axially extending zones and having means for producingdifferent temperature-control effect from the respective zones toequalize the temperature of the strip across its width, mechanism urgingthe deflecting roller against the strip, said mechanism includingautomatic means for changing the force exerted by the deflecting rollerat a rate substantially proportional to the sine of the angle ofdeflection to compensag for changes in said angle of deflection andmaintain the tension of the strip substantially uniform, and means forpreventing change in diameter of the reeled strip from affecting thetension imparted by said mechanism.

12. The combination of apparatus for progressively rolling a metal stripto reduce its thickness, means at spaced points along the length of themetal for causing the progressive movement of the strip, means betweensaid spaced points deflecting the run of the strip at acute angles to astraight line between said points, a torque motor, and mechanismoperated by said motor for applying force to the deflecting means toproduce a tension in the strip, said mechanism including meansconstructed and arranged to change the mechanical advantage of themechanism in accordance with the sine of the angle of deflection so thatthe opposing component forces which tension the strip remainsubstantially unchanged at difierent angles of deflection.

13. The combination of apparatus for progressively rolling a metal stripto reduce its thickness, means at spaced points along the length of themetal for causing the progressive movement of the strip, and atemperature-controlling roller in contact with the run of the stripbetween the spaced points, said roller being divided internally into aplurality of axially extending zones and having means for producingdifferent temperature-control effect from the respective zones toequalize the temperature of the strip across its width.

14. Apparatus for rolling sheet metal including in combination spacedroll stands through which a metal strip moves while working rolls insaid stands operate simultaneously on different portions of the strip, ahollow temperature-controlling roller in contact with the run of thestrip between the roll stands, said roller including partitions dividingthe interior of the roller into several axially extending zones, andmeans for supplying difierent amounts of temperature-controlling fluidto the respective zones to obtain a constant temperature across thewidth of the strip, and mechanism urging the roller against the stripincluding means for moving the roller with variations in the slack inthe run of strip between the roll stands.

15. The combination with a rolling mill having successive roll standswhich operate on difierent portions of the same strip as said striptravels progressively through the mill, of a roller between the rollstands, mechanism for moving the roller against the run of strip betweenthe roll stands and for holding said roller against the strip duringvariations in the slack in said strip, and control means for startingthe operation of said mechanism including means for detecting thepassage of the full width of material behind the forward edge of thestrip.

16. Apparatus for detecting the passage of the full width of metalbehind the forward end of a rolled strip including in combination aphotoelectric relay in a swinging finder, means for swinging the findertransversely of the strip so that the photoelectric relay issuccessively in position to be affected by light from a point justbeyond the edge of the strip and then from points at the edge andprogressively in from the edge, a source of light extending under thestrip in position to supply light to the swinging finder when saidsource of light is not covered by the strip, a source of light adjacentthe edge of the strip for illuminating the finder, and means displacedby the edge of the strip for extinguishing the light from the sourceadjacent the edge of the strip.

17. The combination with successive roll stands through which a metalstrip passes, of means for tensioning the run of strip between said rollstands including a roller which contacts with the strip and deflects itout of a straight run between the stands, and mechanism urging theroller against the strip including a rotary member through which theforce is applied to the roller, said rotary member being of differentdiameter at different points to change the mechanical advantage of themechanism as said member rotates, the rate of change of diameter beingso correlated with the deflection caused by the rotation of said memberthat the force with which. the roller is thrust against the strip variesas a function of the angle of deflection of the strip and keeps thetension in the strip substantially uniform.

18. The combination with successive roll stands through which a metalstrip passes, of strip tensioning means comprising a roller whichcontacts with the strip and deflects it out of a straight run betweenthe roll stands, and mechanism for thrusting the roller against thestrip including a cam which turns in response to changes in the angle ofdeflection to vary the force of the roller against the strip, said camhaving a peripheral contour correlated to the displacement of the rollerso as to vary said force in a manner that keeps the strip tensionconstant during changes in the angle of deflection.

19. The combination with successive roll stands through which a metalstrip passes, of strip tensioning means comprising a roller whichcontacts with the strip and deflects it out of a straight run betweenthe roll stands, and mechanism for thrusting the roller against thestrip including a cable through which force is transmitted to theroller, and a drum on which the cable winds, the drum being of differentdiameter at angularly spaced points with the diameter at each point sorelated to the roller position which corresponds to that position of thedrum that the force transmitted to the roller varies as a function ofthe angle of displacement of the strip and maintains a substantiallyconstant tension in the strip.

20. The method of making sheet metal in a rolling mill in which themetal strip passes successively through roll stands which operatesimultaneously on different portions of the strip, which methodcomprises controlling the shape of the rolls and the temperature of thestrip at the roll stands by controlling the temperature of the rolls,applying a force and deflecting the strip between successive roll standsby a deflecting means, maintaining a substantial deflecting forceagainst the strip to cause the strip to partially envelop and tightlyembrace the deflecting means to control the temperature of the stripmaterial between the roll stands during the rolling of the metal, andcontrolling the temperature of said deflecting means so as to obtain asubstantially uniform temperature across the width of the strip materialto prevent warping and buckling of the strip material.

21. The method of making sheet metal in a rolling mill in which themetal strip passes successively through roll stands which operatesimultaneously on difierent portions of the strip, which methodcomprises controlling the shape of the rolls and the temperature of thestrip at the roll stands by controlling the temperature of the rolls,applying a force and deflecting the strip between successive roll standsby a deflecting means, maintaining a substantial deflecting forceagainst the strip to cause the strip to partially envelope and tightlyembrace the deflecting means to control the temperature of the stripmaterial between the roll stands during the rolling of the metal,controlling the temperature of said deflecting means so as to obtain asubstantially uniform temperature across the width of the strip materialto prevent warping and buckling of the strip material, and equalizingthe temperature of the strip at one or more of the temperature controlregions by selective temperature control at various zones across itswidth to prevent the formation of stresses tending to warp or buckle thestrip.

PERCY W. MATTHEWS.

